Extracted the prisoner being held at Sakhra Ee village
The prisoner that you look for is held at Qarya Sakhra Ee. This is the same location where you find the deployment plans. You can reach the prisoner faster than the plans, because he is in one of the huts in the lower part of the village. You shouldn't have much trouble finding him (look at the picture above). If you need to, you can interrogate one of the guards to learn the specifics. Pick up the prisoner, carry him out of the building and Fulton him.
Extracted the colonel; Extracted all tanks
You can extract the colonel after the convoy stop. However, it is not so easy, because a Cardboard Box will not stop it for long enough and you would have to use some better obstacles. The best way is to simply wait until it reaches Da Smasei Laman and sneak up to the colonel from behind when he moves away from the tanks.
As for extracting the tanks, you can't complete this quest when doing the mission for the first time, because you need to have CARGO 2 upgrade that allows you to transport heavy objects. This upgrade is available only after completing mission 10 (main campaign), because one of the requirements to buy it is to have a Transportation Specialist, who you will find in this mission. When you have the upgrade, play mission 8 one more time. You can stop the tanks using some large obstacle or wait until they reach the fort and Fulton them.